The invention relates to a method for circular grinding during the production of tools made of hard metal on a circular grinding machine that has a workpiece spindle head and a tailstock, whereby work commences using a round rod comprising a starting material.
According to the prior art known from commercial practice, as a rule work commences starting with round rods made of sintered hard metal. These rods then have a grinding overmeasure for the shaft region and are cut to the necessary tool length, or the starting bodies are brought to the required shaft dimension for their entire length using so-called centerless grinding and are then cut into lengths. From the bar pieces that were cut into lengths individually, the tool is then produced from the whole by grinding. For this, the hard metal tools are received during grinding between hollow center punches, tips, or in a chuck.
Grinding occurs either using the conventional grinding method or using the rough grinding method by means of diamond grinding wheels. In any case, multiple instances of re-chucking are required because first the individual bar pieces are produced by grinding and cutting into lengths, where necessary in the reverse sequence as well, and then in subsequent grinding processes that take place on other machines the tool contours are ground and cutting, gradation, spiral cutting, and the like occur.
The known methods in accordance with the prior art work satisfactorily, however they entail the risk of errors in the trueness of the run. These errors are related primarily to multiple instances of re-chucking. Even if work is performed with great attention to precision, such errors in the trueness of the run cannot always be avoided. They are entirely and unpleasantly noticeable on the finished tool. This is particularly true of high-speed processing, for instance in aircraft construction. In this case, cutting tools are used that work at speeds of 30,000 to 60,000 rpms. When processing the light metal parts that are widely used in aircraft construction, even the smallest error in the trueness of the run on the tool is disturbingly noticeable.